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14th of September 2015
Chemistry
Q:

GIVE THE STEPS TO BALANCE COMPLEX CHEMICAL EQUATIONS WITH AN EXAMPLE

Harshita Kanal - Maharashtra - Class X

Monday, September 14, 2015 at 18:30:PM

A:

Using these steps, you can balance any chemical equation.

Steps involved in Balancing a Chemical Equation

 

Consider the chemical reaction between magnesium and oxygen to understand the steps involved in balancing a chemical equation.

 

Step 1

Let us first write the word equation for this reaction.

 

Magnesium + Oxygen →  Magnesium oxide

 

Step 2

Write the chemical equation for the reaction between magnesium and oxygen.

 

Mg  +  O2    MgO

Step 3

Count the number of times an element is occurring on both LHS and RHS in this equation.

Mg  +  O2    MgO 

 

Component

Reactant

Product

Magnesium

1

1

Oxygen

2

1

             

This is an unbalanced equation.

 

Step 4

p  To balance a chemical equation, first draw boxes around each formula. Do not change anything inside the boxes while balancing the equation.

 

p  Choose a reactant or a product that has the maximum number of atoms in it. In that compound, select the element which has the maximum number of atoms. In this equation we shall select MgO i.e. magnesium oxide and the element oxygen in it.

p  To balance the oxygen atoms, let us multiply magnesium oxide molecule by 2 on the right hand side.

The equation can now be expressed as

 

 

Component

Reactant

Product

Magnesium

1

1 X 2 = 2

Oxygen

2

1 X 2 = 2

             

Step 5

There are two oxygen atoms on either side of the equation, but one magnesium atom on the reactant's side and two on the product's side. Therefore, multiply the magnesium atom by 2 on the left hand side.

 

Component

Reactant

Product

Magnesium

1 X 2 = 2

2

Oxygen

2

2

 

The b alanced equation is

 

\ The number of atoms of each element of the reactants = The number of atoms of each element of the products

 

Step 6

Writing Specific conditions on the Arrow

The reaction is carried out in the presence of ‘heat’. On heating, magnesium combines with the oxygen present in the air to form magnesium oxide.

 

Step 7

Writing symbols of the Physical state

p  To make a chemical equation more informative, the physical states of the reactants and products are mentioned along with their chemical formulae.

p  The gaseous, liquid, aqueous and solid states of the reactants and products are represented by the notations (g), (l), (aq) and (s) respectively.

Using these steps, you can balance any chemical equation.

Monday, September 14, 2015 at 18:36:PM